Existing Medium Access Control Protocols Research Articles

A Novel Adaptive TDMA-Based MAC Protocol for VANETs

The medium access control (MAC) protocol plays an important role in vehicular ad-hoc networks (VANETs) to provide efficient broadcast service for safety applications. However, the highly dynamic nature of VANETs, such as high mobility and fast topology change, degrades the performance of existing MAC protocols. In this letter, we propose a novel adaptive Time Division Multiple Access-based MAC (VAT-MAC) protocol for VANETs. VAT-MAC accurately and adaptively optimizes each time frame length by estimating and predicting the number of vehicles within the coverage of a roadside unit. It has been proven by mathematical analysis and simulation experiment that VAT-MAC can significantly improve system scalability and throughput.

Medium access control in wireless sensor networks: a survey

Wireless sensor networks (WSNs) are being integrated across a wide spectrum of military, commercial, and environmental applications, such as field surveillance, environmental monitoring, and disaster management. This variety in WSN applications led to the development of a large number of medium access control (MAC) protocols with different objectives. A common goal of these protocols however, is preserving energy in order to maximise network lifetime. In an effort to facilitate studying existing MAC protocols and developing novel medium access techniques, this paper presents a classification and critical review of existing MAC protocols adopted in different WSN environments. We classify these protocols based on channel access into three main categories: contention-based, contention-free, and hybrid protocols. Cross-layer protocols (involving MAC layer) are also studied. We describe major characteristics of these classes, differences among them, possible improvements, and outline ongoing and future research challenges.

Adaptive RTO for handshaking-based MAC protocols in underwater acoustic networks

Underwater acoustic networks (UANs) are attracting interest in recent decades. The unique characteristics of the underwater acoustic channel, such as long propagation delay, delay variance, and high bit error rate, present challenges for the medium access control (MAC) protocol design in UANs. Most existing medium access control protocols ignore the delay variance which prevents the accurate estimation of round trip time (RTT). The expected RTT value can be used to compute the Retransmission Time-Out (RTO) or the waiting time in MAC. The estimation of RTT is also meaningful for Automatic Repeat re-Quest (ARQ) scheme because the system should ensure reliable data transmissions in the presence of high bit error rate in the underwater acoustic channel. By analyzing the impact of RTO on throughput under the effect of delay variance, we conclude that the fixed RTO is inefficient and RTO should be adaptively set to improve the throughput. We present a novel approach of predicting the RTT using a Bayesian dynamic linear model, and then adjust RTO adaptively according to the predicted values. Simulation results show that the predicted values can adapt quickly to the sample RTT values. Under the effect of RTT fluctuations, the Bayesian algorithm offers performance gains in terms of throughput and prediction performance, comparing with Karn’s algorithm. Our study highlights the value of predicting the RTT using Bayesian approach in underwater acoustic networks.

An Energy Efficient MAC Protocol for Wireless Passive Sensor Networks

Medium Access Control (MAC) protocol is one of the key network protocols that ensure Wireless Sensor Networks (WSNs) maintain high performance during communication. MAC protocol design plays an important role in improving the performances of the whole network. First, Wireless Passive Sensor Networks (WPSNs) and MAC protocols are introduced in this paper. Second, some existing MAC protocols are introduced. Sensor MAC (S-MAC) protocol is analyzed and existing improved backoff algorithms are introduced. A new MAC protocol called Improved Sensor MAC (IS-MAC) is then proposed to solve the problem that the contention window (CW) during carrier sense is fixed in S-MAC protocol. IS-MAC protocol is able to adjust CW in terms of network load, so energy consumption can be decreased. Finally, according to the simulation results on NS2, the proposed protocol has better performance in terms of throughput and energy consumption.

A Performance Evaluation Approach for MAC Protocols of Wireless Multimedia Sensor Networks

The performance evaluation and comparison of any proposed medium access control (MAC) protocol with existing MAC protocol is not always an easy step. Seen that, the re-implementation of existing MAC protocols that will be used in comparison takes significant time. As well, there are points that limit the exploitation of the results of an evaluation in future comparison. In this paper, we propose a performance evaluation approach that resolves these points, and offers other advantages. This approach allows assigning MAC protocol after a predefined evaluation steps to a well-predefined performance class. As well, a performance label is generated for the protocol, which contains information on guaranteed quality of service (QoS) that will allow determining strengths and weakness. The generated label for the evaluated protocol will be used in all future MAC protocols comparison, thing that will eliminate time lost in re-implementation and performance evaluation of the protocol.

A performance evaluation approach for MAC protocols of wireless multimedia sensor networks

The performance evaluation and comparison of any proposed medium access control (MAC) protocol with existing MAC protocol is not always an easy step. Seen that, the re-implementation of existing MAC protocols that will be used in comparison takes significant time. As well, there are points that limit the exploitation of the results of an evaluation in future comparison. In this paper, we propose a performance evaluation approach that resolves these points, and offers other advantages. This approach allows assigning MAC protocol after a predefined evaluation steps to a well-predefined performance class. As well, a performance label is generated for the protocol, which contains information on guaranteed quality of service (QoS) that will allow determining strengths and weakness. The generated label for the evaluated protocol will be used in all future MAC protocols comparison, thing that will eliminate time lost in re-implementation and performance evaluation of the protocol.

Use of Q-learning approaches for practical medium access control in wireless sensor networks

This paper studies the potential of a novel approach to ensure more efficient and intelligent assignment of capacity through medium access control (MAC) in practical wireless sensor networks. Q-Learning is employed as an intelligent transmission strategy. We review the existing MAC protocols in the context of Q-learning. A recently-proposed, ALOHA and Q-Learning based MAC scheme, ALOHA-Q, is considered which improves the channel performance significantly with a key benefit of simplicity. Practical implementation issues of ALOHA-Q are studied. We demonstrate the performance of the ALOHA-Q through extensive simulations and evaluations in various testbeds. A new exploration/exploitation method is proposed to strengthen the merits of the ALOHA-Q against dynamic the channel and environment conditions.

DBR-MAC: A Depth-Based Routing Aware MAC Protocol for Data Collection in Underwater Acoustic Sensor Networks

Due to long propagation delays, routing discovery is very expensive in underwater acoustic sensor networks. Therefore, depth-based routing (DBR) protocols are usually preferred whose routing discovery cost is almost zero. However, DBR protocols working with broadcast medium access control (MAC) bring severe collisions especially in the data collection network. Moreover, in DBR, all the packets are forwarded from deep to shallow nodes along the direction toward the sink node. The directional packet transmissions may lead to load imbalance, where some nodes undertake most loads and we call these nodes key nodes. However, the majority of existing MAC protocols cannot provide the key nodes priority of accessing channel in the collision domain. It is necessary to design a MAC protocol coupling with DBR. In this paper, we adopt a cross-layer approach to propose a DBR aware MAC protocol called DBR-MAC, which smoothly integrates a handshaking-based MAC and a DBR protocol. It improves the throughput, energy, and time efficiency at the cost of fairness. A depth-based transmission scheduling scheme is introduced based on the depth information, angle information, and overheard one-hop neighboring nodes' transmissions to make key nodes have higher priority to access the channel than other nodes. DBR-MAC is a cross-layer scheme and its directional forwarding tries best to forward packets from source to the floating sink node by the least hops. Moreover, an adaptive depth-based backoff algorithm cuts down the backoff time for the nodes and prevents the congestions at key nodes. Extensive simulations show that the throughput, energy, and time efficiency of DBR-MAC outperform existing MAC protocols when applied in the data collection network.

BEST-MAC: Bitmap-Assisted Efficient and Scalable TDMA-Based WSN MAC Protocol for Smart Cities

Smart cities have been envisioned during the last decade. Moreover, various projects have been initiated to bring this concept into reality. Smart city is basically an emergence of the existing and new Information and Communications Technologies (ICT) to make our living standard more safe and digitized. Wireless communications, such as sensors, actuators, intelligent transportation systems, and smart grids, have played a vital role in the dissemination of information under the given circumstances. Similarly, it is hard to declare any city as a smart city without taking benefits from wireless sensor networks (WSNs). However, with new requirements and delay sensitive applications, the existing WSN requires significant alterations at several layers. In this paper, a new time division multiple access (TDMA)-based medium access control (MAC) protocol, called bitmap-assisted efficient and scalable TDMA-based MAC (BEST-MAC), is proposed for adaptive traffic in hierarchical WSNs that can be deployed in the smart cities. BEST-MAC is specifically designed to improve the quality control of such smart cities applications, where diverse traffic is required and loss or delay in data traffic is unacceptable. The main contributions of BEST-MAC include: 1) it uses small size time slots; 2) the number of those time slots is more than the number of member nodes; 3) knapsack algorithm is used to schedule time slots; and 4) short node address (1 B) is proposed to identify the member nodes. First two contributions of BEST-MAC handle adaptive traffic loads of all members in an efficient manner. The knapsack algorithm not only reduces the job completion time of a node but also minimizes the average packet delay with better link utilization. The short node address reduces the control overhead that improves the energy efficiency. The simulation results verify that the proposed BEST-MAC transmits more data with less delay and energy consumption compared with the existing MAC protocols.

Traffic-based energy efficient MAC protocol for wireless sensor networks

The sensor node's battery power shows a key part in the sensor network's lifespan. The various existing medium access control protocols do not consider various factors like the sensor's traffic load and battery life, which lead to more energy consumption. In order to solve this problem, a new protocol called the traffic-based energy efficient MAC TBEMAC protocol is proposed for wireless sensor networks. It includes two stages, namely, the duty cycle adjustment phase and the wakeup schedule phase. In the duty cycle adjustment phase the sensor node's duty cycle is adjusted based on the sensor's traffic load, buffer status and battery life. In the wakeup schedule phase, TBEMAC groups organises the nodes in each corona based on their battery life and traffic load. The active time AT period, is also identified from the wakeup time slots of each node, which greatly reduces idle listening and energy consumption. The simulation results prove that the extension and dynamic adjustment of the duty cycle of the sensor nodes greatly improves data effectiveness, and reduces end-to-end delay.

Adaptive Window Size-Based Medium Access Control Protocol for Cognitive Radio Wireless Sensor Networks

Many existing medium access control protocols for cognitive radio wireless sensor networks waste bandwidth and suffer from delay because of the fixed channel negotiation period in the common control channel. In this paper, we propose a medium access control protocol for cognitive radio wireless sensor networks that adjusts the channel negotiation period based on network density. We simulate the proposed approach and compare it to the performance of the fixed channel negotiation period based approaches. The results show that the proposed approach efficiently utilizes white spaces and increases the aggregated goodput.

Towards Improving the Quality of Present MAC Protocols for LECIM Systems

Wireless networking system is quickly growing in the field of communication technology due to its usefulness and huge applications. To make the system more effective to the users its lower energy consumption, security, reliability and lower cost issues must be considered under any circumstances. Low energy wireless is exceedingly required because the sensors are frequently located where mains power and network infrastructure are not reliably available. The recent development of Low Energy Critical Infrastructure Monitoring (LECIM) has vast applications including: Water leak detection, Bridge/structural integrity monitoring, Oil & gas pipeline monitoring, electric plant monitoring, public transport tracking, Cargo container monitoring, Railroad condition monitoring, Traffic congestion monitoring, Border surveillance, Medical alert for at-risk populations and many more. This proposal Low Energy Critical Infrastructure Monitoring (LECIM) is proposed by the Task Group 4k under IEEE P802.15 WPAN. Although many issues related to its quality are involved, but several Media Access Control (MAC) protocols with different objectives were proposed for LECIM. In this research paper, issues related to energy consumption and wastage in LECIM system, energy savings mechanism, relevant energy conscious MAC protocols have been briefly studied and analyzed. Science Direct, Elsevier, Springer, IEEE Explore, Google Scholar and Wiley digital Library databases were used to search for articles related to the existing MAC protocols well suited for LECIM system. Finally, some ideas have been proposed towards developing energy efficient MAC protocol for LECIM applications in order to fulfill and satisfy the major issues of LECIM quality

Enhanced TDMA based MAC protocol for adaptive data control in wireless sensor networks

In this paper, we propose an adaptive time division multiple access based medium access control (MAC) protocol, called bitmap-assisted shortest job first based MAC (BS-MAC), for hierarchical wireless sensor networks (WSNs). The main contribution of BS-MAC is that: (a) It uses small size time slots. (b) The number of those time slots is more than the number of member nodes. (c) Shortest job first (SJF) algorithm to schedule time slots. (d) Short node address (1 byte) to identify members nodes. First two contributions of BS-MAC handle adaptive traffic loads of all members in an efficient manner. The SJF algorithm reduces node's job completion time and to minimize the average packet delay of nodes. The short node address reduces the control overhead and makes the proposed scheme an energy efficient. The simulation results verify that the proposed BS-MAC transmits more data with less delay and energy consumption compared to the existing MAC protocols.

Toward Practical MAC Design for Underwater Acoustic Networks

Recently, various medium access control (MAC) protocols have been proposed for underwater acoustic networks (UANs). These protocols have significantly improved the performance of MAC layer in theory. However, two critical characteristics, low transmission rates and long preambles, found in the commercial modem-based real systems, severely degrade the performance of existing MAC protocols in the real world. Thus, a new practical MAC design is demanded. Toward an efficient approach, this paper analyzes the impact of these two modem characteristics on the random access-based MAC and handshake-based MAC, which are two major categories of MAC protocols for UANs. We further develop the nodal throughput and collision probability models for representative solutions of these two MAC protocol categories. Based on the analyses, we believe time sharing-based MAC is very promising. Along this line, we propose a time sharing-based MAC and analyze its nodal throughput. Both analytical and simulation results show that the time sharing-based solution can achieve significantly better performance.

A Survey of MAC Layer Issues and Protocols for Machine-to-Machine Communications

With the growing interest in the use of autonomous computing, sensing and actuating devices for various applications such as smart grids, home networking, smart environments and cities, health care, and machine-to-machine (M2M) communication has become an important networking paradigm. However, in order to fully exploit the applications facilitated by M2M communications, adequate support from all layers in the network stack must first be provided in order to meet their service requirements. This paper presents a survey of the requirements, technical challenges, and existing work on medium access control (MAC) layer protocols for supporting M2M communications. This paper first describes the issues related to efficient, scalable, and fair channel access for M2M communications. Then, in addition to protocols that have been developed specifically for M2M communications, this paper reviews existing MAC protocols and their applicability to M2M communications. This survey paper then discusses ongoing standardization efforts and open problems for future research in this area.

A Handshake Based Ordered Scheduling MAC Protocol for Underwater Acoustic Local Area Networks

Underwater acoustic local area networks (UA-LANs) can be used to improve the coverage of an underwater network by introducing a tier of local area communications. Media access control (MAC) is a crucial issue for UA-LANs. Existing MAC protocols for terrestrial WLANs cannot be directly applied to UA-LANs due to the acoustic channel features of limited bandwidth and high and variable propagation delay. In this paper, we propose a handshake based ordered scheduling MAC (HOSM) protocol for UA-LANs. The nodes with data packets to be transmitted first reserve the channel in a channel reservation phase. Then an order list is calculated, and the data packets of these nodes are transmitted according to this order list. We develop a control packets transmission adjustment mechanism to reduce collisions of control packets. The key idea of this mechanism is to utilize the information of propagation delay to adjust the time instant of control packets transmitting. To improve channel utilization, we present a variant Max-Min Ant System algorithm to calculate an optimal order for each data transmission round. Simulation results have confirmed that the proposed protocol can achieve high throughput with low delay and good spatial fairness.

Performance Analysis of Connectivity Probability and Connectivity-Aware MAC Protocol Design for Platoon-Based VANETs

Vehicular ad hoc networks (VANETs) can provide safety and nonsafety applications to improve passenger safety and comfort. Grouping vehicles into platoons in VANETs can improve road safety and reduce fuel consumption. It is critical to design an efficient medium access control (MAC) protocol for platoon-based VANETs. Moreover, because of the space and time dynamics of moving vehicles, network connectivity is an important performance metric to indicate the quality of the network communications and the satisfaction of users. Unfortunately, network connectivity is often ignored in the design of existing MAC protocols for VANETs. In this paper, we study the connectivity characteristics and present a connectivity-aware MAC protocol for platoon-based VANETs. The connectivity probabilities are analyzed for vehicle-to-vehicle and vehicle-to-infrastructure communication scenarios in one- and two-way VANETs, respectively. A multipriority Markov model is presented to derive the relationship between connectivity probability and system throughput. Based on variable traffic status and network connectivity, a multichannel reservation scheme is adopted to dynamically adjust the length of the control channel interval and the service channel interval for the improvement of the system throughput. Analysis and simulation results show that the throughput increases with connectivity probability. However, with a further increase in connectivity probability, the throughput will decrease due to numerous channel contentions.

Reliability comparison of transmit/receive diversity and error control coding in low‐power medium access control protocols

Low-power medium access control (MAC) protocols used for communication of energy constraint wireless embedded devices do not cope well with situations where transmission channels are highly erroneous. Existing MAC protocols discard corrupted messages which lead to costly retransmissions. To improve transmission performance, it is possible to include an error correction scheme and transmit/receive diversity. It is possible to add redundant information to transmitted packets in order to recover data from corrupted packets. It is also possible to make use of transmit/receive diversity via multiple antennas to improve error resiliency of transmissions. Both schemes may be used in conjunction to further improve the performance. In this study, the authors show how an error correction scheme and transmit/receive diversity can be integrated in low-power MAC protocols. Furthermore, the authors investigate the achievable performance gains of both methods. This is important as both methods have associated costs (processing requirements; additional antennas and power) and for a given communication situation it must be decided which methods should be employed. The authors’ results show that, in many practical situations, error control coding outperforms transmission diversity; however, if very high reliability is required, it is useful to employ both schemes together.

Performance Comparison of Energy Efficient Protocols for Wireless Sensor Networks (WSN)

Wireless sensor networks have recently gained a lot of attention from the researches. Wireless sensor networks are often partitioned into clusters, each managed by a cluster head (gateway). This paper reviews medium access control (MAC), an enabling technology in wireless sensor networks. MAC protocols control how sensors access a shared radio channel to communicate with neighbors in small area coverage. It classifies traditional (IEEE 802.11) and existing MAC protocols and a power efficient gathering protocol, known as PEGASIS, as examples of MAC protocol designed specifically for a sensor network. SENSOR MAC sets the radio to sleep during transmissions of other nodes unlike PEGASIS which involves non sleeping cycles. Finally this paper compares the performance of both protocols and displays the results. General Terms Small Sensor Network, Sensor – MAC, PEGASIS

A Scalable CSMA and Self-Organizing TDMA MAC for IEEE 802.11 p/1609.x in VANETs

vehicular ad hoc networks (VANETs) have been a key topic for research community and industry alike. The wireless access in vehicular environment standard employs the IEEE 802.11p/1609.4 for the Medium Access Control (MAC) layer implementation for VANETs. However, the carrier sense multiple access (CSMA) based mechanism cannot provide reliable broadcast services, and the multi-channel operation defined in IEEE 1609.4 divides the available access time into fixed alternating control channel intervals (CCH) and service channel (SCH) intervals, which may lead to the low utilization of the scarce resources. In this paper, a novel multichannel MAC protocol called CS-TDMA considering the channel access scheduling and channel switching concurrently is proposed. The protocol combines CSMA with the time division multiple access (TDMA) to improve the broadcast performance in VANETs. Meanwhile, the dwelling ratio between CCH and SCH changes dynamically according to the traffic density, resulting in the improvement of resource utilization efficiency. Simulation results are presented to verify the effectiveness of our mechanism and comparisons are made with three existing MAC protocols, IEEE MAC, SOFT MAC and VeMAC. The simulation results demonstrate the superiority of CS-TDMA in the reduction of transmission delay and packet collision rate and improvement of network throughput.